Generalized Minimum Variance Controller as a Velocity Loop Controller of a Casting Drum Drive in a Polyester Manufacturing Line

The vast majority of controllers found in manufacturing plants use a combination of Proportional, Integral and Derivative (PID) control. These controllers are easily understood, and there are only three controller values to set up when attempting to achieve an acceptable system response. This paper looks at one industrial application of a PI controller, controlling the speed of a casting drum in a polyester manufacturing plant. The desired objective of the controller is to minimize the variance of the casting drum speed when in steady state. It therefore makes sense to compare a Generalized Minimum Variance Controller with the present PI to see if any improvements can be achieved. NOMENCLATURE s V is the supply voltage, IR is the voltage drop across the motor winding resistance dt di L is the voltage drop across the winding inductance E is the back emf generated by the motor rotation. ω b K = back emf. b K is the back emf constant ω represents the angular velocity. m T equals the motor torque m K is the motor torque constant a I is the armature current. J is the inertia in kgm 2 α is the angular acceleration dt dω in rad/s T Σ is the sum of the torques acting on the drum. E T is the torque developed by the motor L T is the load torque β is the coefficient of dynamic friction L = length of web m E = Young's modulus S = cross section area. V is the downstream roller velocity 2 V is the upstream roller velocity 1 T is the downstream web tension 1 T is the upstream web tension 2 σ is the variance of a white noise input signal